1. Field of the Invention
The present invention relates to a sensor-equipped wheel support bearing assembly having a displacement sensor for detecting a load imposed on a bearing and a rotation sensor for detecting the number of revolution of a wheel, both built therein.
2. Description of the Prior Art
For stabilized run of an automotive vehicle, it is known to provide a wheel support bearing assembly with a rotation sensor for detecting the number of revolution of each of vehicle wheels. In this type of wheel support bearing assembly, the use has been suggested in, for example, the Japanese Laid-open Patent Publication 2003-336652, of sensors, for example, a temperature sensor and a vibration sensor so that in addition to the number of revolutions, vehicle operating conditions useful to the stabilized run of the automotive vehicle can be detected.
To assure a cruising safety of an automotive vehicle in general, the number of revolutions of each of the wheels is detected as a parameter used to control the vehicle cruising performance. However, the use of the number of wheel revolutions is still insufficient and, therefore, it is desired to make use of one or more additional sensors so that the automotive vehicle can be controlled for an improved safety. For this purpose, it is contemplated to control the attitude of the automotive vehicle in dependence on the load acting on each of the vehicle wheels during the traveling of the automotive vehicle.
By way of example, as is well known to those skilled in the art a relatively large load tends to act on the outside wheels during the cornering, on the wheels on one side during the run along the inclined road surface or on the front wheels during the braking, and, thus, a varying load acts on the vehicle wheels. For this reason, if the loads acting on the vehicle wheels can be detected as needed, suspension systems for the vehicle wheels can be controlled beforehand based on results of detection of the loads. By so doing, the attitude control of the automotive vehicle during the traveling thereof, for example, prevention of a rolling motion during the cornering, prevention of downward settling of the front wheels during the braking, and prevention of downward settling of the vehicle wheels brought about by an uneven distribution of live loads can be accomplished. However, no space for installation of the load sensor for detecting the load acting on the respective vehicle wheel is available and, therefore, the attitude control through the detection of the load can hardly be realized.
In the wheel support bearing assembly disclosed in the above mentioned Japanese publication, the detection of the load is accomplished with a displacement sensor fixedly supported by a vehicle-body fitting flange by measuring a gap between the sensor and a surface of an outer member. However, since a detecting portion of the displacement sensor is exposed to the outside, the prior art leaves a problem unsolved as to the durability. Also, considering that the amount of deformation of the outer member is slight, the detecting accuracy is limited accordingly.
Particularly if an attempt is made to install the rotation sensor together with the load sensor, difficulty will be increased as to how those sensors are to be installed in compact.